Most of today's heavily equipped machinery, substantially to the likes of a front end bucket loader, an earth mover, and an excavator, to name a few, operate principally by means of hydraulic fluid flow sustainably operating under moderate to high pressures, typically in the area of 1000-6000 p.s.i. As with most machinery of this type, hydraulic fluid is pumped to a high pressure and transmitted throughout the machinery to various actuators particularly configured and suited to cause a working, hydraulic component to operate and perform work, such as moving a frontward bucket of a front end loader to a desirable upward or downward position, for example. A gasoline- or diesel-operated engine or an electric motor typically serve as means to power the hydraulic pump. Pressurized fluid, on the other hand, is preferentially controlled by means of one or more directional control valves each being equipped with hydraulic valve spools and distributed through a defined network of hoses and tubes. The attractiveness of hydraulic machinery is due in large part to the ample amount of power that can be transferred through the defined network of small tubes and flexible hoses leading to and from the hydraulic valve spools, actuators, reservoirs, and pumps which collectively contribute to the making of a hydraulic circuit. The hydraulic valve spool of one particular type noted in the art can be generally described as comprising a central (neutral) position maintained with springs. Depending on the manufacturer's design configuration, sliding the valve spool to a general fore position opens the valve to permit hydraulic fluid to flow to the actuator and from the actuator to the reservoir. Conversely, when the valve spool is allowed to return to a neutral (center) position, the actuator fluid paths are closed, locking the valve in position. Directional control valves are usually designed to be stackable, with one control valve serving each hydraulic cylinder and one fluid input supplying all the control valves in the stack. The valve spool positions noted above might be actuated by means of a mechanical lever control of the particular type corresponding to the present invention.
Associated with the configuration of the hydraulic circuit is a compilation of structural components, such as the bucket, track, frame, axles, and so forth, fabricated from metallic materials to further the structural integrity of the hydraulic machinery and offer durability for sustained long-term utilization and operation in the field. Given the presence of metallic-fabricated structural components with their associative conductive properties, there exists unforeseeable opportunities for unsafe operation of the hydraulic machinery while in the field. For instance, operation of a metal-tracked excavator or drilling machine while in the field with inappropriate marking of below-grade hazards, such as high powered electrical lines, and unforeseeable interaction and contact thereof with conductive structural components, may have profound impact on the equipment operator's health, perhaps to the extent of serious injury or even death from electrocution.
The art offers a variety of methods and devices for protecting the operator from such serious mishap, notably upon the instance the hydraulic machinery becomes an energized conductor by means of the noted inadvertent contact of the conductive structural components with an electrical source. The most simplistic form of protection might comprise outfitting the equipment operator with protective clothing fabricated with a non-conductive material, such as rubber-lined or insulated clothing, for example. However, any implementation of this level of protection may be inappropriate in some circumstances, particularly where one operates hydraulic machinery in warm or hot environments, among other uninviting situations. Other available protective measures may include safeguards integrated into and made part of the hydraulic machinery. For instance, in a boom truck aerial device, the operator is generally insulated from or isolated from electrical pathways by situating him/her in a non-metallic, workman's basket with further provisions of offering control mechanisms or levers and linkages selectively covered with or fabricated from non-conductive materials, whereas the main structural components of the aerial device, such as the boom, turret, and base, might be fabricated from steel or equivalent material to maintain adequate levels of structural strength. An example of this safeguard approach is illustrated in U.S. Pat. No. 7,416,053 issued to Chard, et al. and entitled “Isolation Mechanism for Electrically Isolating Controls of Boomed Apparatus,” wherein portions of a control handle and associated linkages are fabricated from an electrically non-conductive material insofar to establish a dielectric gap or separation in between the control handle and conductive structural components, a configuration of which suffices to isolate the operator from deadly phase-to-phase or phase-to-ground electrical discharge occurring from inadvertent contact of the aerial device's boom tip with that of an electrical source. Although the safety mechanism present and described in Chard, et al. may adequately serve to protect the operator, particularly with respect to a boomed apparatus operating within a defined environment, its application may be viewed as design limiting and unsuitable for incorporation into other hydraulically operated machinery having unique design characteristics and build requirements.
In addition to the noted unforeseen electrical hazards, there may instances in the field where the equipment operator is momentarily distracted or becomes inattentive to the conditions for safe operation of the hydraulic machinery and inadvertently contacts one or more mechanical lever controls that correspondingly actuates one or more of the valve spools to cause working components to unintentionally operate. It is quite plausible in this case that any inadvertent actuation of control mechanisms of this type may set forth undesirable consequences, possibly to the extent of harming the equipment operator, others situated nearby, and property. The art does offer mechanisms or devices that effectively serve to mitigate inadvertent actuation of working components to some degree, one of which may consists of equipping the directional control valve with a spring that functionally serves to return the control lever and connected valve spool to a neutral, closed position, generally operating to the likes of a momentary switch commonly associated with the electrical arts. However, such configured mechanism may not be timely in preventing the undesirable event from occurring in the first place. In other words, the damage may have arisen to a point of no return.
Accordingly, there remains a need for a single lever control that provides for the manual operation of a hydraulic valve spool of the type present in a directional control valve and commonly associated with hydraulically operated machinery, particularly of which further serves to electrically isolate the operator from electrically charged pathways upon the unforeseen instance the conductive structural components of the hydraulic machinery contacts an electrical source and mitigates occurrences of inadvertent actuation of the directional control valve to cause unintended operation of working, hydraulic components, consequently of which may arise to injury to one or more persons situated nearby and/or damage to property.